Patent attributes
A bicycle seat post assembly includes first and second tubes, which are telescopically arranged, a fluid chamber, which includes a compressible fluid to generate a force to expand the first and second tubes relative to each other, and a positioning structure. The positioning structure includes a support member on one of the first tube and the second tube, a positioning member that pivots about an axis between a first position and a second position, a control unit, which is connected to the positioning member to move the positioning member between the first position and the second position, and a position maintaining member, which is provided on the other of the first tube and the second tube. The position maintaining member includes an engaging portion that engages with the positioning member to maintain a positional relationship between the first and second tubes.